Electric switch with flexible snap action contact elements



Aug. 30, 1966 R. F. OXLEY 3,270,143

ELECTRIC SWITCH WITH FLEXIBLE SNAP ACTION CONTACT ELEMENTS Filed Sept. 18, 1964 2 Sheets-Sheet 1 INVEN'TQE AT Toemaws R. F. OXLEY Aug. 30, 1966 ELECTRIC SWITCH WITH FLEXIBLE SNAP ACTION CONTACT ELEMENTS Filed Sept. 18, 1964 2 Sheets-$heet 2 Q 4 2 0 M 2 1V m Z n/ q M B 3 84 82b 85 i- ZI dfm,% WW

A-r-ToaNzvs United States Patent ice ELECTRIC SWITCH WITH FLEXIBLE SNAP ACTION CUNTACT ELEMENTS Robert Frederick Oxley, Priory Park, Ulverston,

Lancashire, England Filed Sept. 18, 1964, Ser. No. 397,477 Claims priority, application Great Britain, Sept. 19, 1963, 36,963/63; May 28, 1964, 22,151/ 64 12 Claims. (Cl. 200-14) This invention relates to multi-contact electrical switches such as rotary switches, and it is an object of the invention to provide a simple multi-contact electrical switch which is snap-acting. The majority of multicontact switches have moving contacts which wipe the stationary contacts and are thus not snap acting. Certain forms of snap acting multi-contact rotary switches are known but these are clumsy, require considerable mechanical power for operation and are only suitable for low tension use.

According to the present invention, a multi-contact electric switch comprises a number of switch elements each of which has a bowed flexing portion having two positions of stability and arranged to make an electric connection in at least one of the positions and each of which has a pair of trigger members both projecting generally in the same direction from the flexing portion, one on each side of the centre of the bowed portion, and an operating element arranged to move relative to the switch elements to successively engage the two trigger members of each switch element in turn to cause the flexing portions of the switch elements to successively snap from one position of stability to the other and back again.

Preferably each switch element is of integral construction and approximates to the shape of a capital pi(II), the ends being held at a distance apart which results in bowing of the central portion. Thus the switch elements may be of strip such as spring steel but other crosssections, such as rod or wire, and other materials such as plastics are possible. Instead of the switch element being simply bowed by its ends being held together by an external component the switch element may have the ends of the bowed portion held by integral and unbowed portions of the switch member. For example the bowed portion may be provided by a dished centre portion surrounded by an undished periphery. Alternatively the switch element may comprise three strips connected together at each end, the central strips being longer than the other two and thus being bowed.

In a preferred construction in which the switch elements are of strip form, there is a connecting portion between the flexing portion and each trigger member which is part cylindrical and which is carried by and surrounds, or more preferably, is surrounded by a bearing surface on a body member. The body member may have recesses receiving the switch members and affording the bearing surfaces.

Many different electrical arrangements are possible. In the preferred arrangement the flexing portion of each switch element carrier or constitutes a conductive connecting element arranged to engage a pair of spaced terminals when the flexing portion is in one of its two positions of stability. Thus when the switch elements are mounted in recesses in a body member, there may be a pair of terminals in each recess. It would be possible to arrange for each switch element to cooperate with two pairs of terminals, one pair being interconnected in each position of stability of the flexing portion. Each switch element may cooperate with only one terminal and itself be permanently connected to another terminal.

In the preferred arrangement, the switch is a rotary switch and the switch elements are arranged circum- 3,270,148 Patented August 30, 1966 ferentially around an axis and there is an operating element such as a finger, mounted for rotation relative to the switch elements about the axis.

Preferably the trigger members extend generally towards the axis, i.e. in the plane of movement of the operating member, but they may extend axially, i.e. perpendicularly to the plane of movement of the operating memher. In an alternative arrangement the switch is a linear switch with the switch elements arranged in one or more rows.

In a preferred arrangement, the switch elements are arranged in at least two rows, the switch elements of the two rows operating in staggered but overlapped relationship to give a make-'before-break mode of operation.

The invention may be carried into practice in various ways but two particular multi-contact snap acting electric switches will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a side elevation of a rotary switch mounted on a panel with part of the panel broken away;

FIGURE 2 is a cross-section of the switch shown in FIGURE 1 taken on the line IIII of FIGURE 1;

FIGURE 3 is a fragmentary cross section similar to FIGURE 2 and taken on the same line but to an enlarged scale;

FIGURE 4 is a fragmentary elevation taken on the line IV of FIGURE 3;

FIGURE 5 is a plan view of a second form of switch, in this case the switch being a linear switch; and

FIGURE 6 is a cross section of the switch shown in FIGURE 5 taken on the line VI-VI of FIGURE 5.

Referring now to FIGURES 1 to 4 of the drawings, there is shown a rotary switch which includes a hollow cylindrical switching portion 1 made up of five identical switch assemblies 2, a top end cover 3 and a bottom end cover 4. These components are held together by a number of throughbolts which pass through apertures 5 visible in FIGURE 3. A shaft 6 is mounted in concentric apertures in the end covers 3 and 4 and extends upwardly beyond the upper cover 3 and has a knob 7 fixed to its upper end. A threaded sleeve 8 surrounds the shaft 6 and is fixed to the upper surface of the upper cover 3. The sleeve passes through an aperture in a panel 11 and the panel is gripped between a nut 9 and a shoulder 10 on the sleeve to secure the switch 1 to the panel.

As the five switching assemblies 2 are identical only the upper assembly will be described in detail. The assembly includes a body member 12 providing an outer wall in the form of a cylinder whose axial length is small compared 'with the diameter. The body member 12 is formed as a plastic "moulding. The outer surface of the body member -12 is cylindrical but the inner surface has eight grooves or recesses I16 formed in it. Each recess has a part-cylindrical inner wall 14 and curved undercut end walls 14a and 15.- As can be seen in FIGURE 4 each recess is open at the upper end but is closed at the other end to form a shelf 16.

Each recess receives a spring member 2 1 which constitutes a switch element. For convenience of later descripti-on, the six spring members visible in FIGURE 3 have been given the references 21a to 21] and the various parts of these spring members and the corresponding recesses 16 are given the same identifying letters. Each spring member 21 is formed of thin springy strip metal of a width slightly less than the depth of the recess 13 into which it is to be fitted. The spring member 21 has a main flexing portion 22, bearing portions '23 and 24 at the ends of the flexing portion 22 and trigger members 25 and 26 which extend inwards from the bearing portions 23 and 24. The distance between the two bearing portions 23 and 24 is, in the unstressed state of the spring member 21, slightly greater than the corresponding distance between the end walls 14a and 15 of the recess 13 into which the spring member is to be placed. Accordingly when the spring member is placed in the recess the flexing portion 22 can either be bowed either inwards towards the centre of the cylinder as in the case of spring member 21d as shown in FIGURE 3 or bowed outwards away from the centre of the cylinder as in the case of spring member 21b in FIGURE 3. In the latter position the flexing portion 22 rests against the cylindrical wall 14 of the recess. Each spring member is retained in the recess in which it is positioned by an arcuate cover member 31 (see FIGURE 4) which has curved ends to correspond to the end walls 14a and 15 and arcuate sides to correspond to the cylindrical surface 14 of the recess and the inner surface of the body member -12 respectively. Thus, when in position, the closure member 31 forms an upper shelf above the spring member 21 corresponding to the integral shelf 16 provided by the portion of the body member 12 below the spring member 21.

Each spring member 21 is effective, when it is in the condition in which it is bowed outwardly, electrically to connect two radially extending terminals 32 and 3 3. Each switching element thus has two rings of eight circumferentially evenly spaced terminals, the two rings being axially displaced from one another. These terminals which are moulded into the body member 12 have a flat head portion 34 to engage with the spring members 21, an enlargement 35 to retain the terminal in the moulding 12 and radially projecting portion 36 to which a wire may be connected by soldering or wrapping. By way of example all the terminals 33 of the upper switching element shown in FIGURE 1 are connected by a circumferential wire 37 which is connected by a lead wire 38 to a source of electricity. With this arrangement the source can be connected selectively to each of the lower terminals 32 of the upper switching element 2 in turn.

The main shaft 6 carries one radial finger 41 for each switching element, the level of each finger on the shaft being such that it is level with the switching members 21 of the respective switching elements. All five fingers project from the shaft in the same direction.

The operation of the top two switching elements 2 of the switch shown in FIGURES 1 to 4 will now be described in detail, particular reference being made to FIG- URE 3 starting from the position of the finger 41 shown. In this condition the switching element 21a is in the off position while the switching element 21b is in the on position, that is to say the switching member 21b is bowed outwardly so that the contacts 32b and 33b are electrically connected together by the flexing portion 22b of the switching member 2112. the direction of the arrow 42 the finger 41 will first engage the trigger member 25a of the switching element 210. This trigger member will be rocked anti-clockwise as viewed in FIGURE 3 about the bearing portion 230 of this switching element until the flexing portion 22c snaps to its radially outward position in which the contacts 32c and 33c are inter-connected. At this time the switching member 21!; still connects the contacts 32b and 33b. Further rotation of the finger 41 will cause the finger to engage the further trigger member 261) of the switching element 21b thus rocking this trigger member anti-clockwise until at a certain stage the flexing portion 22b is caused to snap inwards so that the connection between the contacts 32b and 33b is broken with a snap action. Further rotation of the fingers will cause the flexing member 22d to make a connection between the terminals 32d and 33d and then the connection between the terminals 320 and 330 will be broken. This sequence will be continued as the shaft 6 is rotated, pairs of terminals 32 and 33 being successively connected together and disconnected, the breaking of a connection made by a given spring member in the top switching assembly occurring shortly after the making of a connection by the next spring member in sequence in the switch- If the shaft is rotated in 4 ing assembly immediately below. The three lower switching assemblies of the switch shown in FIGURE 1 are similarly staggered and connections will be made and broken at the same time as the corresponding connections are made and broken in the top two switch assemblies.

The switch shown in FIGURES 5 and 6 operates on similar principles to that shown in FIGURES l to 4 but is a linearly operated switch instead of a rotary switch. The switch includes a rectangular base member 71 having a central longitudinally extending rectangular well or recess 72. Extending the length of the well are a pair of ribs 76 and 7 4 between which travel a slide block 75. The slide block has a threaded bore through which extends a longitudinally extending coarsely threaded drive shaft 7 6 which is mounted in apertures in bearing brackets 77 and 78. The shaft 76 has a knob 79 and rotation of the knob will cause the nut 75 to move longitudinally along the base 71. The shelf 31 on one side of the well 72 has four spaced rectangular recesses 31a to 8 1d while the shelf 82. on the other side of the well has three recesses 82a to 820 which are staggered with respect to the recesses 81a to 81d. These recesses correspond to the recesses 16 of the switch shown in FIGURES 1 t0 4 and each contains a spring member identical with the spring members 21 of FIGURES 1 to 4. The switching elements 83 have trigger-members 84 which project upwardly out of the apertures and can be engaged by fingers 85 and 86 which project outwardly from the block 75. Moulded into the base member 71 to cooperate with each of the switching members :83 are pairs of terminals 87 and 88 the ends of which are exposed in the bases of the recesses 81 and 82 and which can be connected together by the flexing portions of the spring members.

The operation of the linear switch is similar to that of the rotary switch shown in FIGURES 1 to 4. Thus, as the knob 79 is rotated, the slide block 75 and hence the fingers 85 and 86 are moved linearly past the trigger members 84 of the spring members 81 and -82. Accordingly the flexing portions of the spring members are changed successively from one of their positions of stability to the other and back again to successively make and break the connections between the terminals 87 and 88.

What I claim as my invention and desire to secure by Letters Patent is:

1. A rnulti-contact electric switch comprising a body, a plurality of switch elements mounted on said body, each switch element having a bowed flexing portion having two positions of stability and a pair of trigger members projecting generally in the same direction from opposite ends of the flexing portion, a plurality of fixed electrical contacts mounted on said body each positioned to be engaged by one of said flexing portions when said flexing portion is in one of its two said positions of stability, and an operating element mounted on said body for movement relative to said switch elements to successively engage the two trigger members of each switch element in turn to cause the flexing portions of said switch elements to successively snap from one position of stability to the other and back again.

2. A switch according to claim 1 which includes support means holding the ends of the flexing portion of each switch element at a distance apart which results in bowing of the flexing portion.

3. A switch as claimed in claim 1 in which each switch element approximates to the shape of a capital pi (II).

4. A switch as claimed in claim 1 in which the flexing portion and the trigger members of each switch element are integral with one another.

5. A switch as claimed in claim 4 in which each switch element is made in the form of a shaped strip.

6. A switch as claimed in claim 5 which includes a body member having a plurality of bearing surfaces each switch element being mounted on said body member and having a connecting portion between the flexing portion and each trigger member which is part cylindrical and is carried by one of said bearing surfaces.

7. A switch as claimed in claim 6 in which each said bearing surface surrounds the connecting portion carried by it.

8. A switch as claimed in claim 7 in which said body member has recesses receiving the switch elements and aifording said bearing surfaces.

9. A switch as claimed in claim 8 in which there is at least one electric terminal in the base of each recess positioned to be contacted by the flexing portion of the switch element received in the recess when in one of positions of stability.

10. A multi contact electric switch comprising a body, a plurality of switch elements mounted in a circle on said body about an axis, each switch element having a bowed flexing portion having two positions of stability and a pair of trigger members projecting generally in the same dire-ction from the flexing portion, a plurality of fixed electrical contacts mounted on said body each positioned to be engaged by one of said flexing portions when said flexing portion is in one of its two said positions of stability, and an operating element mounted on said body for rotation about said axis, said operating element having an engaging portion positioned at a radius from said axis to successively engage the two trigger members of each switch element in turn to cause the flexing portions of said switch elements to successively snap from one position of stability to the other and back again.

11. A multi contact electric switch comprising a body, a first series of switch elements mounted in a circle on said body about an axis, a second series of switch elements mounted in a circle on said body about said axis and axially spaced from said first series, each switch element having a bowed flexing portion having two positions of stability and a pair of trigger members projecting generally in the same direction from the flexing portion, a plurality of fixed electrical contacts mounted on said body each positioned to be engaged by one of said flexing 4O portions when said flexing portion is in one of its two said positions of stability, and an operating element mounted on said body for rotation about said axis, said operating element having a first engaging portion for engaging the trigger members of the switch elements of said first series and a second engaging portion for engaging the trigger members of the switch elements of said second series to successively engage the two trigger members of each switch element in turn to cause the flexing portions of said switch elements to successively snap from one position of stability to the other and back again, the relative positions of the switch elements of the first series and the first engaging portion and the switch elements of the second series and the second engaging portion being staggered.

1 2. A multi contact electric switch comprising a body, a plurality of switch elements mounted in a straight row on said body, each switch element having a bowed flexing portion having two positions of stability and a pair of trigger members projecting generally in the same direction from the flexing portion, a plurality of fixed electrical contacts mounted on said body each positioned to be engaged by one of said flexing portions when said flexing portion is in one of its two said positions of stability, and an operating element mounted on said body for linear movement along said row, said operating element having an engaging portion positioned to successively engage the two trigger members of each switch element in turn to cause the flexing portions of said switch elements to successively snap from one position or stability to the other and back again.

References Cited by the Examiner UNITED STATES PATENTS 7/1949 Wise 20067 X 7/ 1949 Sargrove 200-67 X 

11. A MULTI CONTACT ELECTRIC SWITCH COMPRISING A BODY, A FIRST SERIES OF SWITCH ELEMENTS MOUNTED IN A CIRCLE ON SAID BODY ABOUT AN AXIS, A SECOND SERIES OF SWITCH ELEMENTS MOUNTED IN A CIRCLE ON SAID BODY ABOUT SAID AXIS AND AXIALLY SPACED FROM SAID FIRST SERIES, EACH SWITCH ELEMENT HAVING A BOWED FLEXING PORTION HAVING TWO POSITIONS OF STABILITY AND A PAIR OF TRIGGER MEMBERS PROJECTING GENERALLY IN THE SAME DIRECTION FROM THE FLEXING PORTION, A PLURALITY OF FIXED ELECTRICAL CONTACTS MOUNTED ON SAID BODY EACH POSITIONED TO BE ENGAGED BY ONE OF SAID FLEXING PORTIONS WHEN SAID FLEXING PORTION IS IN ONE OF ITS TWO SAID POSITIONS OF STABILITY, AND AN OPERATING ELEMENT MOUNTED ON SAID BODY FOR ROTATION ABOUT SAID AXIS, SAID OPERATING ELEMENT HAVING A FIRST ENGAGING PORTION FOR ENGAGING THE TRIGGER MEMBERS OF THE SWITCH ELEMENTS OF SAID FIRST SERIES AND A SECOND ENGAGING PORTION FOR ENGAGING THE TRIGGER MEMBERS OF THE SWITCH ELEMENTS OF SAID SECOND SERIES TO SUCCESSIVELY ENGAGE THE TWO TRIGGER MEMBERS OF EACH SWITCH ELEMENT IN TURN TO CAUSE THE FLEXING PORTIONS OF SAID SWITCH ELEMENTS TO SUCCESSIVELY SNAP FROM ONE POSITION OF STABILITY OF THE OTHER AND BACK AGAIN, THE RELATIVE POSITIONS OF THE SWITCH ELEMENTS OF THE FIRST SERIES AND THE FIRST ENGAGING PORTION AND THE SWITCH ELEMENTS OF THE SECOND SERIES AND THE SECOND ENGAGING PORTION BEING STAGGERED. 